Move tf, ss2tf, etc into xferfcn module

cwrowley · cwrowley · commit aeba73c8d450 · 2015-04-26T19:16:06.000-04:00
diff --git a/control/__init__.py b/control/__init__.py
@@ -63,7 +63,7 @@
 from .statesp import *
 from .timeresp import forced_response, initial_response, step_response, \
     impulse_response
-from .xferfcn import TransferFunction
+from .xferfcn import *
 from .ctrlutil import *
 from .frdata import FRD
 from .canonical import canonical_form, reachable_form
@@ -86,7 +86,6 @@
 #! of defaults from the main package.  At that point, the matlab module will
 #! allow provide compatibility with MATLAB but no package functionality.
 #!
-from .matlab import tf, ss2tf
 from .matlab import pole, zero, evalfr, freqresp, dcgain
 from .matlab import nichols, rlocus, margin
         # bode and nyquist come directly from freqplot.py
diff --git a/control/matlab/__init__.py b/control/matlab/__init__.py
@@ -78,7 +78,7 @@
 from .. import timeresp
 from .. import margins
 from ..statesp import *
-from ..xferfcn import TransferFunction, _convertToTransferFunction
+from ..xferfcn import *
 from ..lti import LTI  # base class of StateSpace, TransferFunction
 from ..lti import issiso
 from ..frdata import FRD
@@ -388,97 +388,6 @@
 """
 
 
-def tf(*args):
-    """
-    Create a transfer function system. Can create MIMO systems.
-
-    The function accepts either 1 or 2 parameters:
-
-    ``tf(sys)``
-        Convert a linear system into transfer function form. Always creates
-        a new system, even if sys is already a TransferFunction object.
-
-    ``tf(num, den)``
-        Create a transfer function system from its numerator and denominator
-        polynomial coefficients.
-
-        If `num` and `den` are 1D array_like objects, the function creates a
-        SISO system.
-
-        To create a MIMO system, `num` and `den` need to be 2D nested lists
-        of array_like objects. (A 3 dimensional data structure in total.)
-        (For details see note below.)
-
-    ``tf(num, den, dt)``
-        Create a discrete time transfer function system; dt can either be a
-        positive number indicating the sampling time or 'True' if no
-        specific timebase is given.
-
-    Parameters
-    ----------
-    sys: LTI (StateSpace or TransferFunction)
-        A linear system
-    num: array_like, or list of list of array_like
-        Polynomial coefficients of the numerator
-    den: array_like, or list of list of array_like
-        Polynomial coefficients of the denominator
-
-    Returns
-    -------
-    out: :class:`TransferFunction`
-        The new linear system
-
-    Raises
-    ------
-    ValueError
-        if `num` and `den` have invalid or unequal dimensions
-    TypeError
-        if `num` or `den` are of incorrect type
-
-    See Also
-    --------
-    ss
-    ss2tf
-    tf2ss
-
-    Notes
-    --------
-
-    ``num[i][j]`` contains the polynomial coefficients of the numerator
-    for the transfer function from the (j+1)st input to the (i+1)st output.
-    ``den[i][j]`` works the same way.
-
-    The list ``[2, 3, 4]`` denotes the polynomial :math:`2s^2 + 3s + 4`.
-
-    Examples
-    --------
-    >>> # Create a MIMO transfer function object
-    >>> # The transfer function from the 2nd input to the 1st output is
-    >>> # (3s + 4) / (6s^2 + 5s + 4).
-    >>> num = [[[1., 2.], [3., 4.]], [[5., 6.], [7., 8.]]]
-    >>> den = [[[9., 8., 7.], [6., 5., 4.]], [[3., 2., 1.], [-1., -2., -3.]]]
-    >>> sys1 = tf(num, den)
-
-    >>> # Convert a StateSpace to a TransferFunction object.
-    >>> sys_ss = ss("1. -2; 3. -4", "5.; 7", "6. 8", "9.")
-    >>> sys2 = tf(sys1)
-
-    """
-
-    if len(args) == 2 or len(args) == 3:
-       return TransferFunction(*args)
-    elif len(args) == 1:
-        sys = args[0]
-        if isinstance(sys, StateSpace):
-            return ss2tf(sys)
-        elif isinstance(sys, TransferFunction):
-            return deepcopy(sys)
-        else:
-            raise TypeError("tf(sys): sys must be a StateSpace or \
-TransferFunction object.  It is %s." % type(sys))
-    else:
-        raise ValueError("Needs 1 or 2 arguments; received %i." % len(args))
-
 def frd(*args):
     '''
     Construct a Frequency Response Data model, or convert a system
@@ -516,81 +425,6 @@ def frd(*args):
     return FRD(*args)
 
 
-def ss2tf(*args):
-    """
-    Transform a state space system to a transfer function.
-
-    The function accepts either 1 or 4 parameters:
-
-    ``ss2tf(sys)``
-        Convert a linear system into space system form. Always creates a
-        new system, even if sys is already a StateSpace object.
-
-    ``ss2tf(A, B, C, D)``
-        Create a state space system from the matrices of its state and
-        output equations.
-
-        For details see: :func:`ss`
-
-    Parameters
-    ----------
-    sys: StateSpace
-        A linear system
-    A: array_like or string
-        System matrix
-    B: array_like or string
-        Control matrix
-    C: array_like or string
-        Output matrix
-    D: array_like or string
-        Feedthrough matrix
-
-    Returns
-    -------
-    out: TransferFunction
-        New linear system in transfer function form
-
-    Raises
-    ------
-    ValueError
-        if matrix sizes are not self-consistent, or if an invalid number of
-        arguments is passed in
-    TypeError
-        if `sys` is not a StateSpace object
-
-    See Also
-    --------
-    tf
-    ss
-    tf2ss
-
-    Examples
-    --------
-    >>> A = [[1., -2], [3, -4]]
-    >>> B = [[5.], [7]]
-    >>> C = [[6., 8]]
-    >>> D = [[9.]]
-    >>> sys1 = ss2tf(A, B, C, D)
-
-    >>> sys_ss = ss(A, B, C, D)
-    >>> sys2 = ss2tf(sys_ss)
-
-    """
-
-    if len(args) == 4 or len(args) == 5:
-        # Assume we were given the A, B, C, D matrix and (optional) dt
-        return _convertToTransferFunction(StateSpace(*args))
-
-    elif len(args) == 1:
-        sys = args[0]
-        if isinstance(sys, StateSpace):
-            return _convertToTransferFunction(sys)
-        else:
-            raise TypeError("ss2tf(sys): sys must be a StateSpace object.  It \
-is %s." % type(sys))
-    else:
-        raise ValueError("Needs 1 or 4 arguments; received %i." % len(args))
-
 
 def pole(sys):
     """
@@ -1204,24 +1038,6 @@ def lsim(sys, U=0., T=None, X0=0.):
     T, yout, xout = timeresp.forced_response(sys, T, U, X0, transpose = True)
     return yout, T, xout
 
-def tfdata(sys):
-    '''
-    Return transfer function data objects for a system
-
-    Parameters
-    ----------
-    sys: LTI (StateSpace, or TransferFunction)
-        LTI system whose data will be returned
-
-    Returns
-    -------
-    (num, den): numerator and denominator arrays
-        Transfer function coefficients (SISO only)
-    '''
-    tf = _convertToTransferFunction(sys)
-
-    return (tf.num, tf.den)
-
 # Convert a continuous time system to a discrete time system
 def c2d(sysc, Ts, method='zoh'):
     '''
diff --git a/control/xferfcn.py b/control/xferfcn.py
